| Field | Specification |
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| Mfr No | |
| Form | Liquid |
| Function | |
| Plasmid Backbone | |
| Product Type | |
| Production System | |
| Promoter | |
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Overview
AAV-CreERT2 (AAV serotype 2) AAV (AAV2-CreERT2) is an AAV vector packaged in AAV2 under the CMV promoter that delivers CreERT2 to mammalian cells. Researchers commonly use this vector for tamoxifen-inducible conditional recombination; temporal control of gene activation/deletion.
Key elements and design rationale
- Capsid (serotype): AAV2. efficient neuronal transduction with limited spread; widely used for in vitro work and for focal CNS injections.
- Promoter: CMV — human cytomegalovirus immediate-early promoter; strong, broadly active in most mammalian cell types.
- Payload: CreERT2 — fusion of Cre with a mutant estrogen receptor ligand-binding domain (ERT2); recombinase activity is gated by 4-hydroxytamoxifen (4-OHT) administration, allowing temporal control of recombination.
- Genome backbone: Recombinant AAV (single-stranded unless explicitly noted as scAAV) flanked by AAV2 ITRs.
Biological background
CreERT2 is a fusion of Cre recombinase with a triple-mutant ligand-binding domain of the estrogen receptor (ERT2). In the absence of ligand, CreERT2 is sequestered in the cytoplasm by Hsp90; binding of 4-hydroxytamoxifen (4-OHT) — but not endogenous estradiol — releases CreERT2, allowing nuclear translocation and recombination at floxed alleles.
This arrangement allows temporal control of recombination on top of the spatial control already provided by capsid tropism and promoter selectivity, which is particularly useful for studying gene function at defined developmental or experimental time points.
The CMV promoter — human cytomegalovirus immediate-early promoter; strong, broadly active in most mammalian cell types — drives expression of the payload from the AAV cassette in this product. Promoter–capsid combinations together determine where and at what level the payload is expressed.
Research relevance and current trends
- Cre-AAV is widely used to deliver Cre activity to brain regions or cell types without dedicated driver lines, expanding the conditional genetics toolkit.
- Combinations of intersectional approaches (Cre + Flp, or CreERT2 + tamoxifen pulses) allow finer spatial and temporal restriction of recombination.
- AAV vector engineering — including capsid evolution, capsid shuffling, and rational design — continues to expand the spectrum of accessible tissues and cell types.
Common research applications
- Temporally controlled conditional knockout/activation by 4-OHT/tamoxifen.
- Stage-specific activation of Cre-dependent payloads (e.g., reporters, ChR2/DREADDs).
- Lineage tracing initiated at defined time points.
Use this product within experimental designs that include matched controls (capsid, promoter, dose, route) and a transduction validation step before interpreting payload-specific phenotypes.
Notes for experimental interpretation
- Confirm transduction efficiency in the target cell population before drawing payload-specific conclusions; reporter signal alone validates only that the vector reached and expressed in the cells.
- Match AAV dose, capsid, promoter, and route across all conditions when comparing payload to control; differences in any of these confound payload-specific interpretation.
- Avoid repeated freeze–thaw cycles of AAV stocks — aliquot upon first thaw.
- AAV biology, including tropism, can differ between species, strains, ages, and routes — confirm in your specific system.
Choose an AAV capsid based on your target tissue/cell type and delivery route, then benchmark 1–2 alternative serotypes empirically. The capsid (serotype) determines surface attachment and uptake; the cassette and promoter then control where and how strongly expression occurs once cells are transduced. The reference table below summarizes well-established tropism patterns — actual transduction efficiency depends on cell type, route, dose, anti-AAV neutralizing antibodies, and species.
Serotype × tissue tropism reference
| Serotype | Primary attachment / receptor | Best-supported tissues / cells | Common use cases |
|---|---|---|---|
| AAV1 | α-2,3 / α-2,6 N-linked sialic acid | Skeletal muscle, cardiac muscle, CNS neurons, retinal pigment epithelium | Intramuscular and stereotaxic CNS injection; broad neuronal labeling |
| AAV2 | Heparan sulfate proteoglycan (HSPG); coreceptors FGFR1, HGFR | CNS neurons, retinal ganglion cells, kidney, vascular smooth muscle | Stereotaxic CNS injection; intravitreal eye delivery; standard CNS workhorse |
| AAV4 | α-2,3 O-linked sialic acid | Retinal pigment epithelium, ependymal cells of brain ventricles | Subretinal RPE labeling; intracerebroventricular ependyma transduction |
| AAV5 | α-2,3 N-linked sialic acid; PDGFR coreceptor | Airway epithelium, CNS (astrocytes prominent), retinal photoreceptors | Intratracheal lung delivery; CNS astrocyte transduction; subretinal photoreceptor |
| AAV6 | Sialic acid + HSPG; EGFR coreceptor | Skeletal muscle, cardiac muscle, lung, hematopoietic cells (incl. T cells, HSPCs) | Intramuscular delivery; ex vivo HSPC engineering; intratracheal lung |
| AAV8 | 37/67 kDa Laminin receptor (LamR) | Liver (hepatocytes), cardiac muscle, skeletal muscle, retina, pancreas | Systemic IV → liver-directed expression (gold standard); cardiac and pancreatic |
| AAV9 | Terminal N-linked galactose; LamR | Cardiac muscle, skeletal muscle, CNS (crosses BBB in neonates and at high IV dose), liver, lung | Systemic IV for cardiac/skeletal muscle and CNS; intrathecal for spinal cord and DRG |
| AAV-DJ | Engineered chimera (directed evolution from AAV2/8/9) | Broad efficient transduction of mammalian cell lines and primary cells in vitro | In vitro transduction where high efficiency across cell lines is needed; not intended for systemic in vivo use (rapid clearance) |
Selection workflow
- Define the readout. Identify your target tissue/cell type and the experimental window (acute days, weeks, or chronic months).
- Match capsid to tissue. Use the table above as a starting point. For systemic IV, AAV8 (liver), AAV9 (cardiac/skeletal muscle, CNS via BBB), and AAV6 (muscle/lung) are the most common choices. For stereotaxic CNS, AAV2 / AAV5 / AAV9 are first-line. For skeletal muscle, AAV1 / AAV6 / AAV8 / AAV9 all perform well with subtle tissue and species differences.
- Match promoter to expression goal. CMV / CAG / CBA give strong, broadly active expression. Cell-type-specific promoters (CamKIIα, hSyn, GFAP, cTNT, αMHC, TBG, Ttr) restrict expression even when the capsid transduces multiple populations. Capsid-restricted tropism and promoter-restricted expression are independent layers of specificity that can be combined.
- Run a small dose-response. In vitro, test a 10× MOI range with a reporter AAV (e.g., AAV-GFP) of the same serotype to fix optimal MOI before switching to your transgene. In vivo, pilot 2–3 doses with a reporter or matched control vector before scaling.
- Use proper controls. Match capsid serotype, promoter, and dose between test and control vectors. Empty / Null capsid controls (e.g., AAV-Null) match for capsid- and dose-related effects independent of payload; LacZ or GFP-only vectors match for transgene-expression load.
Practical considerations
- Anti-capsid neutralizing antibodies. Pre-existing immunity against AAV2 and several other serotypes is common in human and primate studies and reduces transduction. This is less of a concern in inbred laboratory mouse strains but is reportable in NHP and human-relevant work.
- Route matters as much as capsid. The same capsid can give very different tropism by intravenous vs. intramuscular vs. intrathecal vs. stereotaxic vs. subretinal injection. The "best" capsid for a tissue is route-specific.
- Single-stranded vs. self-complementary (scAAV). Standard recombinant AAV is single-stranded and requires second-strand synthesis after entry, leading to a 1–3 week onset to peak expression. scAAV bypasses this step (faster onset, ~3–7 days) at the cost of half the packaging capacity (~2.4 kb vs. ~4.7 kb).
- ITR backbone. Nearly all recombinant AAVs — across capsid serotypes — use AAV2 ITRs. The capsid identity and the ITR identity are independent design choices.
- Empirical validation is required. Tropism summaries are starting points. Final serotype selection should be validated in a pilot experiment in your specific cell line, animal model, and route of administration.
Selected references on AAV biology and tropism: Wu Z, Asokan A, Samulski RJ. Adeno-associated virus serotypes: vector toolkit for human gene therapy. Mol Ther 2006;14(3):316–327. Zincarelli C, Soltys S, Rengo G, Rabinowitz JE. Analysis of AAV serotypes 1–9 mediated gene expression and tropism in mice after systemic injection. Mol Ther 2008;16(6):1073–1080. Srivastava A. In vivo tissue-tropism of adeno-associated viral vectors. Curr Opin Virol 2016;21:75–80. Pillay S, et al. An essential receptor for adeno-associated virus infection. Nature 2016;530:108–112.
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